If you're not receiving emails from Useme, check your spam folder. If there are no messages from Useme there, contact your email provider and ask them to add useme.com domain to the exception list.
You can also download all documents related to you deal from your Useme account.
How to download the tax invoice from your Useme account?
To download the invoice or any documents related to the deal, log in to your Useme account and go to Dashboard → Deals → Chosen deal → Documents tab.